We study the effects of quenched disorder on the two-dimensional d-wave superconductors ͑SCs͒ at zero temperature by Monte Carlo simulations. The model is defined on the three-dimensional ͑3D͒ lattice and the SC pair field is put on each spatial link as motivated in the resonating-valence-bond theory of the high-T c SCs. For the nonrandom case, the model exhibits a second-order phase transition to a SC state as density of charge carriers is increased. It belongs to the universality class different from that of the 3D XY model. Quenched disorders ͑impurities͒ are introduced both in the hopping amplitude and the plaquette term of pair fields. Then the second-order transition disappears at a critical concentration of quenched disorder, p c Ӎ 15%. Implication of the results to cold atomic systems in optical lattices is also discussed.Effects of disorder on phase structures and phase transitions have been studied for various systems. In particular, the high-T c materials are microscopically highly nonuniform and it is suggested that there exists a spin-glass-like phase near the phase transition point of superconductivity ͑SC͒ at low temperatures ͑T͒. 1 Furthermore, existence of a Bose glass was recently suggested in the Mott-insulating phase of cold atomic systems in random potentials. 2 In the present paper, being motivated in part by these observations, we shall study effects of quenched disorders on SCs by using a lattice Ginzburg-Landau ͑GL͒ model of unconventional d-wave SCs. The model in its pure case was introduced as the GL theory of the resonating-valence-bond ͑RVB͒ field for the t-J model, 3 and the case of including interaction with the electromagnetic ͑EM͒ field has been investigated recently. 4 We expect that this model also describes superfluid phase of fermionic atoms in cold atomic systems in optical lattices. There, the effects of disorders can be investigated well under control. 5 We are interested in quantum SC phase transition of the two-dimensional ͑2D͒ model at T = 0. The model in pathintegral representation is described in terms of the following RVB-type Cooper pair field U xj ,